spa-api/app/Providers/BroadcastServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Facades\Broadcast;

class BroadcastServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        Broadcast::route(['middleware' => ['web']]);

        Broadcast::auth('channel-name.*', function ($user, $id) {
            return true;
        });
    }

    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}